22692-57-5Relevant articles and documents
Dethreading of Tetraalkylsuccinamide-Based [2]Rotaxanes for Preparing Benzylic Amide Macrocycles
Martinez-Cuezva, Alberto,Rodrigues, Leticia V.,Navarro, Cristian,Carro-Guillen, Fernando,Buriol, Lilian,Frizzo, Clarissa P.,Martins, Marcos A. P.,Alajarin, Mateo,Berna, Jose
, p. 10049 - 10059 (2015/11/03)
The dethreading of a series of succinamide-based [2]rotaxanes bearing benzylic amide macrocycles is reported herein. These transformations proceeded quantitatively either under flash vacuum pyrolysis, conventional heating, or microwave irradiation. Studying the size complementarity of the stoppers at the ends of the thread and the cavity of the macrocycle allowed us to set up the best substituents for implementing the extrusion of the thread from the interlocked precursors. A variety of 1H NMR kinetic experiments were carried out in order to evaluate the rate constants of the dethreading process, the half-life times of the rotaxanes, and the influence of temperature and solvents on these processes. The use of dibutylamino groups as stoppers yielded the rotaxane precursor in a reasonable yield and allowed the quantitative deslipping of the rotaxane. The overall process, including the rotaxane formation and its further dethreading, has been exploited for preparing benzylic amide macrocycles enhancing, in most cases, the results of the classical (2 + 2) condensation and other reported stepwise syntheses. The kinetics of the dethreading process is fairly sensitive to the electronic effects of the substituents on the isophthalamide unit or to the electronic nature of the pyridine rings through a conformational equilibrium expanding or contracting the cavity of the interlocked precursor.
Quenching of Aromatic Hydrocarbon Fluorescence by α,ω-Diamino-alkanes
Davidson, R. Stephen,Whelan, Terence D.
, p. 241 - 246 (2007/10/02)
α,ω-Bisdiethylamino-, α,ω-dipyrrolidino-, and α,ω-dipiperidino-alkanes quench the fluorescence of aromatic hydrocarbons in cyclohexane solution.The efficiency of quenching is dependent upon the length of the chain linking the two nirogen atoms.For chains containing 6 methylene groups linking the nitrogen atoms, quenching is proposed to occur via a multi-collisional process.These diamines are more effective quenchers than their monoamine counterparts.The effect of chain length is barely noticeable when solvents more polar than cyclohexane are used. α,ω-Bis-(N-methylanilino)-alkanes are efficient quenchers of aromatic hydrocarbon fluorescence, but the efficiency does not depend on the length of the linking chain.The quantum yield of exciplex fluorescence is attenuated when the linking chain contains two or three methylene groups.